Subject: My first hand routed SIP call - Good example for new users

From: [email-masked] (Dan Kolis)
Date: Wed, 21 Jan 2004 10:08:22 -0500

Hello... Regarding making SIP hop for you in your first session!

As any programmer knows, getting the first "Hello world" back from a new
computer language is the hardest hurdle. After that, you look back after a
few thousand pages of code and say... "easy". Doing this all a little at a
time will teach you it in a deep sense. If you just want to make a call and
not know how it works: Bum a quarter and find a payphone instead!

Anyway, here is a canned example of a TCP hand coded SIP session that works
as of this morning. SIP tends to just hangup without an response code unless
the session is reasonably well formed. The below works.

Thanks Henning S. for inventing SIP! and making the client exist on
columbia.edu as below.

This is via TCP using a telnet client under linux. I telneted to the linux
box from home using a telnet client under Windows. Anyway, it couldn't make
the UDP open, but that is "hello world plus" so once you have the response
code to parse... the low level is working, obviously.

The below is a "telephone call" to Columbia university via internet
hand routed without software. This is a good way to learn it in depth.
The best actually. The top block is what I hand entered, and the bottom
is the (HA!) "phone switch". Stimus and response, hand entered. Somewhere 
I read some Telnet clients inserts extra [CR LF[ sequences which goofs up
the [CR LF] detection. SO enter it carefully by hand once and you will be far
ahead. If you get a "200 Bad thing" etc you know your firewalls and what
have you is not in the way.

Regards,
Dan K

  TELNET
  telnet> open sip.columbia.edu 5060
  Trying 128.59.39.127...
  Connected to ren.cc.columbia.edu.
  Escape character is '^]'.
  INVITE sip:[email-masked] SIP/2.0
  Via: SIP/2.0/UDP 169.130.4.4
  FROM: <sip:[email-masked]>
  TO: <sip:[email-masked]>
  call-id: 123456@[email-masked]
  content-length: 0

  SIP/2.0 400 Transaction tupel incomplete (9/SL)
  Via: SIP/2.0/UDP 169.130.4.4;received=204.101.26.60
  FROM: <sip:[email-masked]>
  TO: <sip:[email-masked]>;tag=b27e1a1d33761e85846fc98f5f3a7e58.16fb
  call-id: 123456@[email-masked]
  Server: Sip EXpress router (0.8.12 (i386/linux))
  Content-Length: 0
  Warning: 392 128.59.39.127:5060 "Noisy feedback tells:  pid=13647
  req_src_ip=204.101.26.60 req_src_port=4829 in_uri=sip:[email-masked] 
  out_uri=sip:[email-masked] vi
  a_cnt==1"

Example: 4769498 "First SIP call"

Regards,
Dan Kolis